P1378: PLERIXAFOR AND GRANULOCYTE COLONY STIMULATING FACTOR FOR POOR MOBILIZERS IN PATIENTS UNDERGOING AUTOLOGOUS PERIPHERAL HEMATOPOIETIC STEM CELL TRANSPLANTATION: SINGLE INSTITUTION STUDY
Authors: J. El Cheikh, K. Terro, S. El Warrak, L. Sharrouf, M. A. Timonian, F. Ismail, A. Zahreddine, N. Kreidieh, I. Abou Dalle, N. Moukalled, A. Bazarbachi
Journal: HemaSphere (2022)

Background: Autologous hematopoietic stem cell transplantation (ASCT) has become the mainstay treatment for many hematological malignancies and solid tumors. An adequate number of stem cells must be collected for better ASCT outcomes, which is challenging in 5-30% of patients. To improve mobilization, plerixafor is used along with granulocyte colony-stimulating factor (GCSF). Aims: Our aim is to examin the efficacy of Plerixafor in improving PSC mobilization, identify the factors influencing mobilization outcomes and point out the differences in the outcomes post PSC infusion. Methods: We conducted a retrospective single center study involving patients who received plerixafor pre-ASCTs between January 2013 and December 2020 at a tertiary care center in Lebanon. We identified a total of 84 consecutive adult patients. All patients identified were poor mobilizers and have eventually received Plerixafor either as pre-emptive use before first apheresis in those with peripheral CD34+ stem cells (PSC) <2.5 x106 cells/Kg, or after failure of first apheresis in those with PSC ≥2.5 x106 cells/Kg. The primary end point of the study was to evaluate the efficacy of Plerixafor and to identify factors associated with better mobilization. Secondary endpoints included evaluating characteristics of poor mobilizers, stem cell yield pre and post-plerixafor, as well as the time to neutrophils and platelets engraftment. Using one sample T test, univariate and multivariate analysis, we examined the efficacy of Plerixafor in improving PSC mobilization, identified the factors influencing mobilization outcomes and pointed out the differences in the outcomes post PSC infusion. Results: The median age at ASCT was 52.7 years (22-74) with 61% male predominance. Multiple myeloma was the most prevalent disease 64% followed by Lymphoma 32%. The majority of patients were in complete remission 64% at the time of ASCT. Most patients received proteasome inhibitor-based induction therapy 67% and Melphalan-based conditioning therapy 68%. The median follow up from ASCT was 9 months (1-59). It was noted that greater BMI is a significant factor for better PSC collection whether premobilization (P=0.003), or post Plerixafor mobilization (P=0.024). Moreover, Multiple Myeloma patients showed better mobilization using Plerixafor (P=0.049). Using Plerixafor along with GCSF in poor mobilizers post GCSF alone showed a statistically significant increase in the collected PSC mean from 0.67 x106 cells/Kg to 4.90 x106 cells/Kg (P< 0.001) with a failure rate only for 12 patients (15%). The infusion of PSC > 2.5x106cells/Kg has shown a 3 days decrease in time to platelet engraftment (P=0.021) and a 36% decrease in progression/relapse rate (P=0.025). Image:Summary/Conclusion: Plerixafor is effective in increasing the PSC yield in poor mobilizers. Low BMI and hematologic malignancies other than Multiple Myeloma are risk factors for poor mobilization. More studies should be performed to establish more risk factors, helping us to identify poor mobilizers more accurately and initiate Plerixafor mobilization early on, to be able to improve the engraftment and to decrease the relapse rate accordingly.